Phase equilibria in the system Nd2O3|P2O5|H2O at 500°C under 100 MPa and synthesis of NdP5O14 crystals

Abstract

Phase equilibria in the system Nd~o3-P20S-H2o was studied under a hydrothermal cond1t1on at SOOoC under 100 MPa by a quenching technique using encapsuled samples. Equilibria among Nd phosphates; NdPS014' NdP309 and NdP04, and liquid phase could be atta1ned within 24 h. The stability fields for liquid (L), NdPS014+L, NdPS014+NdP309+L, NdP309+L, NdP309+NdP04+L, Nd~04+L and NdPo4+Nd(OH)3+H20 have been determined. The composition of the 11quid phase witP which NdPSo14 and NdP309 or NdP309 and NdPo4 could coexist was 3% Nd203-80% P20S-17% H~O or 4% Nd203-73% P20S-23% H 2 0 respectively, at SOO C under 100 MPa. A phase diagram was constructed under this condition. Crystal growth of NdPS014 were tried under the equilibrium condition. Diamond-shaped crystals 0.3 rom in size were grown at SOO°C for 4 days under 100 MPa. Crystals tended to show aggregation and surface roughness at lower growth temperatures. The crystals with polyhedral shape and maximum O.S rom in size were grown at 6S0°C. IneroductionSince Danielmeyer and Weber(l) found an effective laser action in NdP S o14 crystal, this material has been studied extensively for laser action (2-S) , crystal structure (6-8) , ferroelectric behavior(9,10) and crystal growth (11)(12)(13)(14)(15)(16)

Crystal chemistry of ultraphosphates

“…NdP 5 0, 4 Reinvestigation at 773 Κ under 100 MPa of the Nd 2 0 3 -P 2 0 5 -H 2 0 system by Yoshimura, Fujii and Somiya (1981) in order to elaborate a method of crystal growth for NdP 5 0i 4…”

Synthesis and characterization of new superionic triorthophosphates

“…The alkaline component was taken (ii) Hydrothermal method: the synthesis of phosin the form of molar solution with a definite phates by hydrothermal method is quite cornmolarity and this solution (NaOH solution) acts plicated and it is recent [7,8] Since these compounds show a negative terndiameter) using Teflon liners of capacity 25 ml. A perature coefficient of solubility under hydrothermal conditions, the furnace temperature was slowly raised up to a predetermined point and held for 10 proves the mechanical strength of the material.…”