Growth and properties of a noncentrosymmetric polyphosphate CsLa(PO₃)₄crystal with deep-ultraviolet transparency

Abstract

A single crystal of CsLa(PO3)4has been successfully grown, and it exhibits a remarkable deep-UV cutoff edge of 167 nm.

Crystal growth and optical characteristics of beryllium-free polyphosphate, KLa(PO3)4, a possible deep-ultraviolet nonlinear optical crystal

“…It can be seen that the SHG efficiency of KLa(PO 3 ) 4 is about 0.7 times that of KDP. This value is comparable to most of the deep-UV NLO phosphate crystals, such as Rb 2 Ba 3 (P 2 O 7 ) 2 (0.3 × KDP), CsLa(PO 3 ) 4 (0.5 × KDP), Ba 3 P 3 O 10 Cl (0.6 × KDP), Ba 5 P 6 O 10 (0.8 × KDP), and RbBa 2 (PO 3 ) 5 (1.4 × KDP)17181922. Moreover, the results indicate that KLa(PO 3 ) 4 is a type I phase-matchable material in visible region according to the rule proposed by the Kurtz and Perry method35.…”

“…This remarkable deep-UV absorption edge not only is much shorter than those of well-known KTiOPO 4 and KDP crystals34, but also is shorter than those of the phosphate NLO crystals reported recently, such as BaP 3 O 10 Cl (180 nm)17, RbBa 2 (PO 3 ) 5 (163 nm)18, Ba 5 P 6 O 20 (167 nm)19, and CsLa(PO 3 ) 4 (167 nm)22. It is also comparable to those of beryllium borates, such as KBBF (155 nm)5, NaSr 3 Be 3 B 3 O 9 F 4 (170 nm)9, and LiNa 5 Be 12 B 12 O 33 (169 nm)11, and those of beryllium-free borates, such as BaAlBO 3 F 2 (165 nm)34 and Ba 4 B 11 O 20 F (<175 nm, from powder diffuse reflectance spectrum)13.…”

“…Figure 3(b) shows that the constant pressure specific heat capacity of KLa(PO 3 ) 4 varies as a function of temperature. Its specific heat at 25 °C (0.585 J·g −1 ·K −1 ) is higher than that of CsLa(PO 3 ) 4 (0.513 J·g −1 ·K −1 )22. Moreover, the specific heat of KLa(PO 3 ) 4 increases almost linearly from 0.580 to 0.866 J·g −1 ·K −1 with temperature increase from 20 to 500 °C, which means that the KLa(PO 3 ) 4 crystal can endure even more thermal energy at high temperature.…”

“…1.165 eV) were calculated to be 1.5614, 1.5698 and 1.5693, respectively. Correspondingly, the optical birefringence (Δ n ) of the KLa(PO 3 ) 4 crystal is 0.0084, which is higher than that of CsLa(PO 3 ) 4 by 24%22. That just explains the fact the KLa(PO 3 ) 4 crystal is phase-matchable at 1064 nm, whereas CsLa(PO 3 ) 4 is not.…”

“…In light of this strategy, we have studied a condensed metaphosphate of cesium and lanthanum crystal, CsLa(PO 3 ) 4 , which indeed exhibits a very short absorption edge (167 nm) and moderate powder SHG efficiency22. Unfortunately, it is not phase-matchable.…”