Eu opean Summi on In e disciplina y Resea ch and De elopmen - An In e na ional Resea ch Con e ence
Published By C ys al Pen Publica ion, Pe ambalu , Tamil Nadu, India - www.c ys alpen.in
ESIRD - 2025 P oceedings, Da e: No embe 30, 2025, ISBN Numbe : 978-93-49435-80-3
95
MECHANOCHEMICAL-ASSISTED SYNTHESIS AND
CHARACTERIZATION OF PRISTINE AND GD3+ DOPED
COWO4 COMPOUNDS
V. Anbalagan*, K. Dinaka an** & P. P abukan han***
* Ma e ials Chemis y Lab, Depa men o Chemis y, Mu hu angam Go e nmen A s
College, Vello e, Tamil Nadu, India
** Depa men o Chemis y, Thi u allu a Uni e si y, Vello e, Tamil Nadu, India
*** Depa men o Chemis y, Go e nmen A s and Science College, K.V. Kuppam,
Vello e, Tamil Nadu, India
Ci e This A icle: V. Anbalagan, K. Dinaka an, P. P abukan han. (No embe 2025). Mechanochemical-
Assis ed Syn hesis and Cha ac e iza ion o P is ine and GD3+ Doped COWO4 Compounds. In P oceedings o
he Eu opean Summi on In e disciplina y Resea ch and De elopmen (pp. 95-102). Pe ambalu , Tamil Nadu,
India: C ys al Pen Publica ion.
ISBN: 978-93-49435-80-3
Publishe Websi e: www.c ys alpen.in
Copy Righ : © 2025 C ys al Pen Publica ion (CPP). All igh s ese ed. This is an open access a icle
dis ibu ed unde he e ms o he C ea i e Commons A ibu ion License (CC BY), which pe mi s un es ic ed
use, dis ibu ion, and ep oduc ion in any medium, p o ided he o iginal wo k is p ope ly ci ed.
DOI:
Abs ac :
P is ine and Gd3+ doped CoWO4 compounds we e syn hesized by mechanochemical assis ed. The
XRD, EDAX, FT-IR spec oscopy s udy indica es ha pu e phase o ma ion o he wo ami e- ype wi h
monoclinic sys em. Scanning elec on mic oscopy s udy sugges s ha smoo h su ace mo phological wi h
uni o m dis ibu ion o pa icles. Op ical abso p ion, pho oluminescence, EPR and EDAX analysed e el ha
Gd3+ is subs i u ed in he Co2+ in o CoWO4 la ice. When he Gd3+ was inco po a ed in he CoWO4 compound
he abso p ion peak posi ion signi ican ly changed, whe eas luminescence p ope y was killed. The e is a
de ia ion in he composi ion o Co, i s indica e ha when he concen a ion o Gd inc eases in CoWO4.
Key Wo ds: CoWO4; XRD; op ical p ope ies; EPR; and TG/DTA s udies.
1. In oduc ion:
Me al ungs a es a e a ac i e ma e ials and ha e ecei ed conside able esea ch in e es due o hei
in iguing luminescence and s uc u al p ope ies. As a p- ype semiconduc o , CoWO₄ has been he mos widely
s udied ma e ial o a ious echnological applica ions such as ca alysis, senso s, displays, and op oelec onics.
I is well es ablished ha he addi ional doping will induce he s uc u al and magne ic changes in he hos
sys ems [1-2].A. Sen, P. P amanik [3] (2001) epo ed he pho oluminescen p ope ies o hyd o he mally
syn hesized Eu³⁺-doped ZnWO₄. Jani e al [5] (1995) s udy he g ow h and spec al analysis o Ho³⁺-doped
ZnWO₄.. Recen ly, Nikl e al [6] (2000) epo ed he luminescen ea u es o he CoWO₄:Ce³⁺ nanos uc u e.
Sco e al (2002) [7] epo ed he Ln³⁺-doped YPO₄ nano/mic os uc u es wi h unable luminescen colo s. The
e ec o Nd impu i ies on he op ical, dielec ic, and elec ical p ope ies o PbWO₄ single c ys als was epo ed
by Dai e al (2007) [8]. The b igh whi e upcon e sion luminescence om E ³⁺, Tm³⁺, and Yb³⁺ doped CaSnO₃
powde s has been epo ed by Thong em e al. (2009) [9].
Fu he , i is epo ed ha he lan hanide ions possessing special 4 in a shells a e ecognized as
excellen candida es o luminescence cen e s o he doped ino ganic phospho sys ems due o hei many
op ical ad an ages. Recen ly, Dy, as one elemen belonging o he lan hanide amily, doped phospho s ha e
been he ocus o nume ous in es iga ions because o hei unique op ical p ope ies [8] and p omising
applica ions in op oelec onics [9]. Many me al ungs a es exhibi such p ope ies as will make hem sui able o
po en ial applica ions in di e en a eas o echnology. The CoWO₄ is a ma e ial ha has been conside ed o
ex ensi e s udies o pho oluminescence (PL), op oelec onic de ices, scin illa ing ma e ial, mic owa e
dielec ics, and ca alysis [6] whe e he p ope ies o hese ma e ials can be achie ed by a well-in ended syn he ic
echnique [7-8]. The ungs a es a e ound o be highly a ac i e and sui able o di e en me hodological
applica ions such as solid-s a e lase s [5], scin illa o s [6], op oelec onic de ices, besides being p omising
candida es o supe -ha d ma e ials [7], which a e use ul and p omising candida es.
To da e, se e al chemical syn hesis p ocesses, such as sonochemical, hyd o he mal, co-p ecipi a ion,
e c., ha e been used o he p epa a ion o me al ungs a e, especially o he wol ami e nanoc ys als. Syn hesis
o me al ungs a e nanoc ys alli es was done wi h low- empe a u e e hylene glycol as a sol en . Simila ly, Dai e
al (2007) [8] p oposed he oom empe a u e syn hesis and p ope ies o mul i unc ional doped ungs a e
nano ods. Among hese di e en me hods, he solu ion-based chemical syn he ic me hods play a c ucial ole in
he design and p oduc ion o ine ce amics and ha e been success ul in o e coming many o he limi a ions o
he adi ional solid-s a e, high- empe a u e me hods. The use o solu ion chemis y can elimina e majo
p oblems such as long di usion pa hs, impu i ies, and agglome a ion, which will esul in a p oduc wi h
Eu opean Summi on In e disciplina y Resea ch and De elopmen - An In e na ional Resea ch Con e ence
Published By C ys al Pen Publica ion, Pe ambalu , Tamil Nadu, India - www.c ys alpen.in
ESIRD - 2025 P oceedings, Da e: No embe 30, 2025, ISBN Numbe : 978-93-49435-80-3
96
imp o ed homogenei y. Howe e , we me hods ha e disad an ages such as complica ed syn he ic s eps, use o
expensi e equipmen , high syn he ic empe a u e, and long sin e ing ime. On he o he hand, due o excessi e
ene gy consump ion, complex appa a us, and echniques, he solid-s a e eac ion becomes g adually unpopula
and unsa is ac o y. Howe e , solid-s a e ma e ial syn hesis by he me a he ic ou e is eme ging as a iable
al e na i e app oach o syn hesizing high-quali y no el ino ganic ma e ials in a sho amoun o ime. He e we
epo he syn hesis o p is ine and Gd-doped CoWO₄ by a no el solid-s a e mechanochemical app oach me hod,
and he e ec s o he dopan on he s uc u es and su ace mo phology wi h composi ion and op ical p ope ies
we e epo ed.
2. Expe imen al - Syn hesis o p is ine and Gd3+ ions doped CoWO4 Compounds:
Na₂WO₄.2H₂O, Gd(CH₃COO)₃, and CoCl₂.6H₂O ob ained om Al a Aesa , USA, we e used as
p ecu so s o he syn hesis o he cobal ungs a e (CoWO₄) and Gd³⁺-doped CoWO₄ compounds. Syn hesis o
CoWO₄ was ca ied ou by eac ing a well-g ound mix u e o CoCl₂ and Na₂WO₄ in a mola a io o 1:1 in he
mechanochemical app oach me hod. The a ain p oduc we e washed wi h deionised wa e o emo e he
sodium chlo ide eac ion by p oduc and d ied a 90°C. Syn hesis o a ious mole concen a ions (1, 3, and 5
mole %) o Gd-doped CoWO₄ compounds was ca ied ou in a simila manne by eac ing o a well-g ound
mix u e o Na₂WO₄, Gd(CH₃COO)₃, and CoCl₂, as men ioned abo e. Syn hesis o cobal ungs a e (CoWO₄) and
Gd-doped CoWO₄ compounds was acco ding o he ollowing chemical eac ions:
Na2WO4 + CoCl2 CoWO4 + NaCl
Na2WO4 + CoCl2 + (1, 3 and 5mole %) Gd(CH3COO)3 CoWO4:Gd + NaCl
3. Resul and Discussion:
3.1 XRD Analysis:
Figu e 1 shows he XRD pa e ns o he syn hesized p is ine and Gd-doped CoWO₄ ungs a es. The
p is ine and Gd-doped ungs a es ollow a wol ami e-like monoclinic c ys al s uc u e wi h he space g oup o
P2/c. Thei la ice pa ame e s a e as ollows: a = 4.947 Å, b = 5.682 Å, c = 4.66 Å, and b = 90.0° o p is ine and
Gd-doped CoWO₄.. The la ice pa ame e s o he CoWO₄ compound unde conside a ion a e consis en wi h he
alues epo ed in [10] and abula ed by he Join Commi ee on Powde Di ac ion S anda ds (JCPDS); ile No.
(72-0479) o cobal ungs a e. The pa e n o p is ine and Gd-doped CoWO₄ indica es he main di ac ion
peaks o he monoclinic CoWO₄ phase a 2q = 31.6°, 39.1°, 45.2°, 56.2°, 66.14°, and 75.3°, which co espond o
he (020), (012), (211), (231), and (232) c ys allog aphic planes, espec i ely. As Figu e 1 e eals, no
cha ac e is ic peaks om non- eac ing s a ing ma e ials a e de ec ed on he XRD pa e ns o he syn hesized
CoWO₄ ungs a es, indica ing ha he p oduc s ob ained a e single-phase ma e ials. Wi h he doping o Gd, no
new peak was ound due o Gd(CH₃COO)₃, which is asc ibed o he inco po a ion o Gd in o he Co la ice si e.
Wi h espec o he Gd doping concen a ion o 1, 3, and 5 mole %, he e is no peak shi obse ed, bu he
in ensi y inc eased g adually. This may be associa ed wi h he la ice dis o ion induced by Gd ions in o he
CoWO₄ c ys al s uc u e, which leads o a la ge ionic adius o dopan ions, and also Gd³⁺ ions in he Co² si e
enla ge he c ys alline size o he CoWO₄.. Table 1 lis s he ull wid h a hal maximum (FWHM) alues o he
(020) e lec ion peak o p is ine and Gd-doped CoWO₄ compounds. The FWHM o he (020) peak o Gd-doped
CoWO₄ is highe han ha o p is ine CoWO₄ due o c ys al la ice s ain occu ing in Gd-doped CoWO₄.. In
con o mi y, he a e age c ys alline size o he p is ine and Gd-doped CoWO₄ assessed using Sche e ’s equa ion
[D = 0.9 l/b cos q, whe e b is he FWHM o he di ac ion line in adians and l is he X- ay wa eleng h] is
based on using he (020) e lec ion a 31.6°.The a e age c ys alline size o he p is ine and CoWO₄ compound
could be de e mined by employing Sche e ’s o mula, and i was ound o be 973-1059 nm.
Table 1: FWHM, c ys alline size and a omic concen a ion o p is ineand Gd doped CoWO4 compounds
Compounds
FWHM o GAXRD
peak (020) (deg.)
C ys alline
size (nm)
Composi ion (A omic Pe cen age)
Co
W
O
Gd
P is ineCoWO4
0.02847
973
16.92
16.38
66.7
0.00
1 mole % Gd doped CoWO4
0.02893
1012
16.08
16.32
66.62
0.98
3 mole % Gd doped CoWO4
0.02921
1034
14.32
16.31
66.58
2.79
5 mole % Gd doped CoWO4
0.03023
1059
12.88
16.29
66.51
4.32
Eu opean Summi on In e disciplina y Resea ch and De elopmen - An In e na ional Resea ch Con e ence
Published By C ys al Pen Publica ion, Pe ambalu , Tamil Nadu, India - www.c ys alpen.in
ESIRD - 2025 P oceedings, Da e: No embe 30, 2025, ISBN Numbe : 978-93-49435-80-3
97
Figu e 1: Powde XRD spec a o p is ineand Gd-doped CoWO4
3.2 UV-Visible Spec al S udies:
Op ical abso p ion measu emen is a widely used echnique o con i ming dopan subs i u ion in o he
hos la ice. A he same ime, he change in elec onic band s uc u e also can be iden i ied using UV-Vis
abso p ion spec a. The UV-Vis abso p ion spec a o syn hesized p is ine and Gd-doped CoWO₄ compounds
a e shown in Figu e 2. The s ong abso p ion maximum o 231-385 nm was obse ed o all he samples. Due o
he high c ys allini y, he samples ha e shown mo e p ominen UV abso p ion maxima, which imply ha he e
is di ec cha ge ans e be ween he me al and ligand wi hin he (WO₄²⁻) complex. The e was no addi ional
abso p ion due o he Gd seen in he UV-Vis spec a, demons a ing he subs i u ion o Gd in o he Co la ice
[11]. By he addi ion o Gd, only he small shi in he abso p ion band was obse ed owa ds lowe wa eleng hs
o he samples. This may be due o he ac i e in e ac ion o i alen ca ions wi h di alen ions. The abso p ion
peak a 231-385 nm does change signi ican ly, whe eas peak b oadening dec eases in magni ude, possibly due
o he o ma ion o a wide dis ibu ion o Gd ions in he wol ami e s uc u e o he CoWO₄ compound. The
s ong d-d ansi ion band was obse ed in he isible and a - isible egions (490-656 nm and 1057-1800 nm)
and co esponds o he d-d ansi ion o Co²⁺ ions in he CoWO₄ sys em, which also shi ed sligh ly owa ds
lowe wa eleng hs wi h espec o Gd doping concen a ion.
Figu e 2: UV-Vis abso p ion spec a o p is ine and Gd-doped CoWO4
Eu opean Summi on In e disciplina y Resea ch and De elopmen - An In e na ional Resea ch Con e ence
Published By C ys al Pen Publica ion, Pe ambalu , Tamil Nadu, India - www.c ys alpen.in
ESIRD - 2025 P oceedings, Da e: No embe 30, 2025, ISBN Numbe : 978-93-49435-80-3
98
3.3 Scanning elec on mic oscopy (SEM) and Ene gy Dispe si e X-Ray Spec oscopy (EDAX) Analysis:
Figu e 3 (a-d) ep esen s he SEM mic og aphs o p is ine and Gd-doped CoWO₄ compounds. F om
he SEM images, mo e in o ma ion on he g ains and na u e o he samples can be seen. Cap u ed SEM images
clea ly show he o ma ion o sel -agg ega ed pa icles, highly homogeneous and cubical in shape. I is clea ly
seen ha he pa icles a e highly agg ega ed and eme ge in a well-c ys alline na u e. The addi ion o Gd in o
CoWO₄ made no changes in he su ace mo phology excep he c ys al diame e , which is in he ange o 900-
1100 nm. This esul indica es ha he addi ion o Gd e ains hei mic os uc u e wi hou al e ing he c ys alline
s uc u e and mo phology. Wi h an inc ease in he doping concen a ion, he pa icle size was inc eased
signi ican ly, and he uni o m pa icle dis ibu ion was also obse ed. This esul u he con i ms he comple e
inco po a ion o Gd on o he Co la ice si e.
The elemen al chemical analysis has ca ying ou using EDAX di ec ly a ached o he SEM
ins umen . The expe imen al EDAX spec a o p is ine and 5 mole % Gd-doped CoWO₄ we e exposed in
Figu es 3 (e- ). The a omic concen a ions o he p ima y elemen s p esen in he p is ine and Gd-doped CoWO₄
compounds a e gi en in Table 1.EDAX spec a ob iously designa e he p esence o unc ional elemen s o Co,
Gd, W, and O wi h app op ia e concen a ions wi hou any impu i ies, which con i ms he s oichiome ic
concen a ion o he elemen s. F om Table 1, i can be obse ed ha he e is de ia ion in he composi ions o Co
when he concen a ion o Gd inc eases in CoWO₄ compounds. The esul s indica e ha Gd migh ac as a
subs i u e a he Co si e in he CoWO₄ compound sys em.
Eu opean Summi on In e disciplina y Resea ch and De elopmen - An In e na ional Resea ch Con e ence
Published By C ys al Pen Publica ion, Pe ambalu , Tamil Nadu, India - www.c ys alpen.in
ESIRD - 2025 P oceedings, Da e: No embe 30, 2025, ISBN Numbe : 978-93-49435-80-3
99
Figu e 3 (a- ): SEM mic og aphs (a) p is ine CoWO4 , 1 mole % Gd3+ ions doped CoWO4 (b), 3 mole % Gd3+
ions doped CoWO4 (c), 5 mole % Gd3+ ions doped CoWO4 (d), EDAX spec a o p is ine CoWO4 (e) and 5
mole % Gd3+ ions doped CoWO4 ( )
3.4 FT-IR Spec a S udies:
To de e mine he chemical s uc u e o he p is ine and Gd³⁺-doped CoWO₄ compounds, he Fou ie -
ans o m in a ed (FT-IR) spec a we e obse ed o e he equency ange o 4000-400 cm⁻¹ as shown in
Figu e 4. The in ense band ha appea ed in he low- equency egion o 400-1000 cm⁻¹ belonged o he
cha ac e is ic de o ma ion modes o Co-O, W-O, and W-O-W b idges. The IR spec a below 565 cm⁻¹ could be
asc ibed o he de o ma ion modes o W-O bonds in WO₆ oc ahed a o he de o ma ion o W-O-W b idges [12].
The weak bands appea ing a 849 and 726 cm⁻¹ could be associa ed wi h he asymme ical s e ching o he O-
W-O ib a ion mode and he W-O bond s e ching in he (W₂O₄)ₙ chain, espec i ely. When compa ed o he
p is ine CoWO₄, he Gd³⁺-doped sample has shown he b oad ib a ional band a a ound 430 cm⁻¹, which
co esponds o he Co-O and asc ibes he inco po a ion o Gd in o he Co la ice. While inc easing he Gd
concen a ion, he e is no isible band due o he Gd-O-Co o Gd-O being seen, his con i ms he homogenous
dispe sion o Gd wi hin he CoWO₄ ma ix. And also, when Gd concen a ions we e inc eased in he CoWO₄
la ice, does no change he band posi ion.
The abso p ion o CO₂ om he a mosphe e a he CoWO₄ su ace was iden i ied om he sha p band
posi ioned a abou 2353 cm⁻¹ in he FTIR spec a. F om he igu e i can be seen ha he in ensi y o he O-C-O
s e ching band inc eases wi h inc easing he concen a ion o Gd³⁺.This may be due o he p esence o Gd³⁺ ions
in he CO₂ si e ha abso bs mo e CO₂ om he ai a mosphe e. The OH s e ching ib a ion o su ace-abso bed
o in e nally bonded wa e molecules accoun ed o he s ong in ense band appea ing a 3759 and 3556 cm⁻¹..
The bending mode o H-O-H was loca ed a abou 1634 cm⁻¹.This mainly a ises om in e nally bonded wa e
molecules o physically adso bed wa e molecules.
Figu e 4: FT-IR spec a o p is ine and Gd3+ doped CoWO4 compounds
Eu opean Summi on In e disciplina y Resea ch and De elopmen - An In e na ional Resea ch Con e ence
Published By C ys al Pen Publica ion, Pe ambalu , Tamil Nadu, India - www.c ys alpen.in
ESIRD - 2025 P oceedings, Da e: No embe 30, 2025, ISBN Numbe : 978-93-49435-80-3
100
3.5 Pho oluminescence (PL) S udies:
Figu e 5 shows ypical oom empe a u e pho oluminescence (PL) spec a o p is ine and Gd³⁺-doped
CoWO₄ compounds. F om he igu e i can be seen ha he h ee cha ac e is ic emission bands a a ound 364,
467, and 634 nm o he p is ine CoWO₄ compound asc ibe he in insic op ical beha io o he hos sys em. The
luminescen e iciency seems o be closely ela ed o he p ocess o syn hesis o ob aining pa icles ha a e no
agglome a e bu well- o med c ys als. In compa ison o he p is ine CoWO₄ compound, he 1, 3, and 5 mole %
Gd-doped CoWO₄ exhibi a ed shi o a highe wa eleng h egion in he emission band, wi h a dec ease in he
in ensi y. The luminescen band in highe wa eleng h should be associa ed o he empe amen o
semiconduc ing band gap. I is no iceable in he PL spec a ha he sudden d op in he in ensi y a doping Gd
(1, 3, and 5 mole %) concen a ion demons a es ha he small o la ge amoun o Gd ac s as he luminescen
kille in he CoWO₄ ma ix [13-16]. Acco dingly s e n luminescen educe was expe ien ial in di e en
concen a ions o Gd-doped CoWO₄ compounds. While be capable o seen s a ing he igu e, he e is no o he
band ela ed o he Gd in CoWO₄ ha has been p agma ic, and ye high concen a ions supplemen a y con i m
he whole inco po a ion o Gd in Co la ices. The de iciency o deep-le el isible luminance in PL spec a
con i ms he de ec - ee c ys alline na u e o he p is ine CoWO₄ compound.
Figu e 5 : Pho oluminescence spec a o p is ine and Gd-doped CoWO4
3.6 EPR Spec al S udies:
An analysis o Co2+ EPR spec a is no s aigh o wa d because he spec a can be eco ded usually a
low empe a u es because o a e y as elec on spin-la ice elaxa ion, which p oduces s ong EPR line
b oadening. Mo eo e , Co2+ ions (3d7 con igu a ion wi h S = 3/2, I = 7/2) can appea bo h a high-spin (S = 3/2)
and a low-spin (S = 1/2) con igu a ions and ha e di e en cha ac e is ics in e ahed al and oc ahed al
coo dina ion. Figu e 6 shows he EPR spec a o p is ine and Gd3+ doped CoWO4 in solid s a e eco ded a 77 K.
In his igu e wo g oups o cobal hype ine lines a e shown. The b oad EPR ea u e om 123 and 210 gauss
unambiguously indica es he p esence o he high spin Co2+ {S =3/2, d7} in which he EPR ansi ion occu s
wi hin he lowe K ame s double {ms = ½} a 77 K o he p is ine CoWO4 compound. Bu 1 mole % Gd3+
doped CoWO4 compound has his egion well- esol ed hype ine s uc u e appea . Howe e Gd ions
concen a ion has inc eased his egion o un esol ed spec a [17-18]. Un esol ed hype ine s uc u e a gyy
gzz {g} may be a ibu ed o he 59Co nuclei {I = 7/2}. The g alue is 5.7 0.2. In second egion he na ow
in ense signal wi h g11 = 2.004 his a ibu ed o an elec on which ans e ed om WO2- o Co2+, when Gd3+
ions concen a ion his high, he in ensi y peaks we e dec eased bu no change he peaks posi ion. This
phenomenon is a ibu ed o signi ican con ibu ions om exci ed o bi al s a es and spin-o bi coupling.
Whe eas g>g11 when he A2g s a e has he lowes ene gy.
Eu opean Summi on In e disciplina y Resea ch and De elopmen - An In e na ional Resea ch Con e ence
Published By C ys al Pen Publica ion, Pe ambalu , Tamil Nadu, India - www.c ys alpen.in
ESIRD - 2025 P oceedings, Da e: No embe 30, 2025, ISBN Numbe : 978-93-49435-80-3
101
Figu e 6: EPR spec a o p is ine and Gd3+ doped CoWO4 compounds
3.7 The mog a ime y/Di e en ial The mal Analysis (TG/DTA):
Typical empe a u e e sus mass change o he p is ine and 5 mole % Gd³⁺-doped CoWO₄ a e shown in
(TGA) Figu e 7a.The s epwise c ys alliza ion wi h espec o empe a u e is as ollows: he ini ial weigh loss in
he TGA cu e a a ound 200°C is associa ed wi h he decomposi ion o me al sal and impu i y e apo a ion. In
con inuous hea ing, he majo weigh loss obse ed abo e 200°C is mainly a ibu ed o he c ys alliza ion
p ocess aking place. Fu he , e y small and g adual weigh loss ollowed by he pla eau egion in he TGA
cu e beyond 400°C.By adding he Gd in o he Co si e, he c ys alliza ion empe a u e educes signi ican ly, as
shown in Figu e 7a.
In ela ion o he mal decomposi ion (di e en he mal analysis) o he pu e and 5 mole % Gd³⁺-doped
CoWO₄, Figu e 7b is shown. In he p is ine CoWO₄ compound, ou he mal decomposi ion s eps we e
obse ed {81, 302, 648, and 755°C}.Thei peak indica es an exo he mic na u e. The i s one had an exo he mic
peak assigned o he elimina ion o wa e and gases abso bed on he powde su ace. O he peaks we e
exo he mic, being assigned o a combus ion eac ion ha led o he o ma ion o an in e media e me a-s able
compound wi h he espec i e me al oxide.
Figu e 7 (a-b): (a) TGA spec a o p is ine and 5 mole % Gd3+ doped CoWO4
(b) DTA spec a o p is ine and 5 mole % Gd3+ doped CoWO4
4. Conclusion:
A no el mechanochemical solid-s a e me a hesis app oach has been employed o syn hesize
echnologically impo an p is ine and Gd-doped CoWO₄ ma e ials. This me hod has dis inc ad an ages in
e ms o simplici y and easy scale-up and is ela i ely inexpensi e wi h high yield. The X- ay di ac ion
analysis clea ly shows ha he Gd-doped CoWO₄ compounds a e single-phase in he monoclinic (wol ami e)
s uc u e. Op ical abso p ion edge ene gies o he p is ine and Gd-doped CoWO₄ syn hesized in his s udy ha e
been de e mined. Op ical s udies o p is ine and Gd-doped CoWO₄ exhibi s he in ense abso p ion posi ion
Eu opean Summi on In e disciplina y Resea ch and De elopmen - An In e na ional Resea ch Con e ence
Published By C ys al Pen Publica ion, Pe ambalu , Tamil Nadu, India - www.c ys alpen.in
ESIRD - 2025 P oceedings, Da e: No embe 30, 2025, ISBN Numbe : 978-93-49435-80-3
102
be ween 231-385 nm, which con i ms he excellen op ical beha io o he monoclinic (wol ami e) s uc u e.
The small wa eleng h shi was owa ds he lowe wa eleng h egion o he doped samples, add essing he
in e ac ion o he Gd³⁺ ion wi h he CoWO₄ s uc u e. SEM showed well-de ined mo phology o p is ine and
Gd-doped CoWO₄ p epa ed by his me hod. By Gd doping he e is no inding o any o he possible seconda y
phases in luminescence, and also he absence o deep-le el isible emission in he PL spec a con i ms he
de ec - ee c ys alline na u e. The absence o Gd³⁺ ions in he EPR spec a is assumed o be due o a e y sho
elaxa ion ime o he Gd³⁺ sys em ha esul s in a e y b oad line. TG/DTA indica es ha he e is no phase
ansi ion possibili y and an exo he mic peak cu e is obse ed.
Acknowledgemen s:
P. P abukan han would like o acknowledge he inancial suppo o Science and Enginee ing Resea ch
Boa d (SERB)-Empowe men and Equi y Oppo uni ies o Excellence in Science [EMEQ] p og am
(F.No.SB/EMEQ-259/2014), Depa men o Science and Technology (DST), India.
Re e ences:
1. A. Sen, P. P amink, J. Eu . Ce am. Soc. 21, 745-750 (2001)
2. A. Phu uang a , T. Thong em, S. Thong em, Cu . Appl. Phys. 10, 342-345 (2010)
3. A. Sen, P. P amanik, J. Eu . Ce am. Soc. 21, 745-750 (2001)
4. A. K. S i aman, A.K. Tyagi, The mochim. Ac a 406, 29-33 (2003)
5. M.G. Jani, F.L. Na anjo, N.P. Ba nes, K.E. Mu ay, G.E. Locka d, Op . Le . 20, 872-874 (1995)
6. M. Nikl, P. Bohacek, N. Mihoko a, M. Kobayashi, M. Ishii, Y. Usuki, V. Babin, A. S olo ich, S.
Zazubo ich, M. Bacci, J. Lumin. 87, 1136-1139 (2000)
7. H.P. Sco , Q. Williams, E. Kni le, Phys. Re . Le . 88, 15506-15509 (2002)
8. Q. Dai, H. Song, X. Bai, G. Pan, S. Lu, T. Wang, X. Ren, H. Zhao, J. Phys. Chem. C 111, 7586-7592
(2007)
9. S. Thong em, S. Wannapop, T. Thong em, Ce am. In . 35, 2087-2091 (2009)
10. Liang Zhen, Wen-Shou Wang, Cheng-Yan Xu, Wen-Zhu Shao, Lu-Chang Qin Ma e ials Le e s 62,
1740-1742 (2008).
11. T. Rajesh Kuma , P. P abukan han, G. Ha ichand an, J. Thee hagi i, A. Mee a Moydeen, G. Du ai, P.
Kuppusami, T. Ta a chuk, J. Ma e . Sci. Ma e . Elec on. 29, 5638-5648 (2018).
12. R. Nasse , H. Zhou, A.B.G. T abelsi, F.H. AlKallas, H. Elhouiche , J.M. Song, J. Ene gy S o age 68,
107763 (2023).
13. T Rajesh Kuma , P P abukan han, G Ha ichand an, J Thee hagi i, Si a aman Chand aseka an, J
Madha an, Ionics, 23, 2497-2507 (2017)
14. J. Julie Josephine Joy, N. Vic o Jaya, J Ma e Sci: Ma e Elec on 24, 1788-1795 (2013)
15. P P abukan han, T Rajesh Kuma , G Ha ichand an, Ma e ials Resea ch Exp ess, 2, 096102 (2015)
16. G. Sun, Q. Gao, S. Tang, R. Ling, Y. Cai, C. Yu, H. Liu, H. Gao, X. Zhao, A. Wang, J. Elec on.
Ma e ., 51, 3205-3215 (2022).
17. T. RajeshKuma , P. P abukan han, G. Ha ichand an, J. Thee hagi i, Te iana Ta a chuk, T.
Maiyalagan, Gilbe oMaia, M. Bououdina, J Solid S a e Elec ochem.22,1197-1207 (2018)
18. K. Mageswa i, T. Ba ani, J. Madha an, P. P abukan han, Hyb id Ad ances, 8, 100377 (2025).
