We determ
ined the crystall
izat
ion reg
ion of KGd(PO
3)
4 (KGP)
in the ternary system Gd
2O
3-K
2O-P
2O
5, the
isotherms of saturat
ion temperature and s
ix ne
ighbor
ing phases: KPO
3, GdPO
4, KGdP
4O
12,Gd(PO
3)
3-orthorhomb
ic, Gd(PO
3)
3-monocl
in
ic, and GdP
5O
14. We successfully grew KGP s
ingle crystalsby the top-seeded solut
ion growth (TSSG) slow cool
ing method. To opt
im
ize the growth process andobta
in h
igh-qual
ity KGP crystals, solut
ion compos
it
ion and seed or
ientat
ion were analyzed and a growthdev
ice was added. KGP
is
isostructural to KNd(PO
3)
4, crystall
izes
in the monocl
in
ic system
P2
1 and thecell parameters determ
ined are
a = 7.2701(11),
b = 8.3818(8), and
c = 7.9608(10) &Ar
ing;,
![](/<font color=)
images/g
ifchars/beta2.g
if" BORDER=0 ALIGN="m
iddle"> = 91.776(12)
![](/<font color=)
images/ent
it
ies/deg.g
if">,
Z = 2, and
V = 484.87(11) &Ar
ing;
3. We stud
ied how they evolved as the temperature
increased from roomtemperature to 773 K and observed an almost
isotrop
ic l
inear thermal expans
ion, the tensor of wh
ich wealso calculated. In the room temperature to 1273 K range analyzed, we found that KGP
irrevers
iblydecomposed at 1142 K. The second harmon
ic eff
ic
iency, qual
itat
ively measured by the Kurtz method,was at least s
im
ilar to that of KH
2PO
4 (KDP).