How do single crystals differ from polycrystalline samples ...

• Typical transporting agents i
I2, Br2, Cl2, HCl, NH4Cl, H2, H

• Temperature gradient is typic
using a two-zone furnace.

• Tubes are usually SiO2, unle
metal tubes (Pt, Au, Nb, Ta,

• Examples :
Growth of Fe3O4 crystals
Fe3O4 (s) + 8HCl (g) Æ FeCl2
(Endothermic)

include:
H2O, AlCl3, CO
cally created and controlled
ess reactive, in which case
W) are used.

2 (g) + FeCl3 (g) + 4H2O (g)

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• Growth of ZrNCl crystals
ZrNCl (s) + 3HCl (g) Î ZrCl
(Exothermic)

• Growth of Ca2SnO4 crystals
SnO2 (s) + CO Æ SnO (g) +

SnO (g) + CO2 (g) + 2CaO (
• Chemical Vapor Transport is

high quality crystals from po
rates are usually quite slow
approach more attractive for
applications.

l4 (g) + NH3 (g)

s
+ CO2 (g)
(s) Æ Ca2SnO4 (s) + CO (g)
s a good method of growing
owders. However, growth

(mg/h) which makes this
r research than for industrial

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Laser Heated Pedes
雷射加熱提拉生長法

The LHPG technique is deri
melting method and capable
variety of crystal fibers. In pr
fibers approximately 20~300
this technique.

stal Growth (LHPG)
法

ived from the zone
e of producing a large
ractice, one can grow
0um in cross section with

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Nonlinear laser crystal as a b
heated pedestal growth, spec
second harmonic generation
K3Li2−xNb5+xO15+2x single crys

J. Ph

As the LHPG technique, the concen
species as a function of the pulled c
the following equation:
C(.x) = C0[1 − (1 − k) exp(−πr2k x /V

where C0 is the dopant concentratio
obtained, r is the radius of the pulle
melt and k is the equilibrium distribu
phase diagram.

we chose to pull the fibres at rates r
h−1. At the end of the growth, the fib
8 h under an oxygen flow.

blue converter: laser
ctroscopic properties and
n of pure and Nd3+-doped
stal fibres

hys. D: Appl. Phys. 29 (1996) 3003–3008.

ntration C of each chemical
crystal length x is described by

V)]

on in the feed and in the first liquid
ed fibre, V is the volume of the
ution coefficient given by the

ranging between 20 and 33 mm
bres were annealed at 900 0C for

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Cross section of an a-axis
oriented KLN fibre: (a)
experimental cross section of a
K3Li2−xNb5+xO15+2x, x = 0.24/ fibre:
(b) idealized growth symmetry.

Surface morphologies of a
K3Li2−xNb5+xO15+2x, x = 0.24/ fibre:
(a) view of c-plane; (b) view of b-
plane.

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