Mechanical, thermal and spectral characteristics of Nd
3+
:Sr
6
YSc(BO
3
)
6
crystal
Feifei Yuan
a
, Wang Zhao
b
, Shijia Sun
a
, Lizhen Zhang
a
, Yisheng Huang
a
, Zhoubin Lin
a,
⇑
a
Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 350002 Fuzhou, China
b
Anhui Key Laboratory of Low Temperature Co-fired Materials, Department of Physics, Huainan Normal University, 232038 Huainan, China
article info
Article history:
Received 10 October 2014
Received in revised form 16 January 2015
Accepted 17 January 2015
Available online 9 March 2015
Keywords:
Laser crystal
Crystal growth
Thermal characteristics
Spectral properties
Nd
3+
:Sr
6
YSc(BO
3
)
6
crystal
abstract
A crystal of Nd
3+
:Sr
6
YSc(BO
3
)
6
was grown successfully by the top-seeded solution growth method. The
average laser-induced damage thresholds are 1.76 GW/cm
2
for (0 01) face and 1.47 GW/cm
2
for (1 00)
face at 1064 nm radiation, respectively. The average Vickers hardness of (1 00) and (0 0 1) faces are 629
and 545 N/mm
2
, respectively. The thermal expansion coefficients are 12.3 10
6
K
1
along a-axis and
9.39 10
6
K
1
along c-axis, respectively. The thermal conductivity is about 2.3 W/m K at room
temperature. The polarized spectral properties were investigated in detail. Based on the Judd–Ofelt
theory, the intensity parameters were obtained. The results show that Nd
3+
:Sr
6
YSc(BO
3
)
6
crystal is a
potential laser crystal.
Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction
With the rapid development of diode-pumped solid-state
lasers, research on high efficient diode-pumped materials become
more and more important. Nd
3+
:YAG and Nd
3+
:YVO
4
are commer-
cially available laser crystals, but limited to low Nd
3+
(1 at.%)
doping concentration and narrow absorption bands near the diode
output wavelength of 808 nm.
The borate crystals are a type of excellent laser gain media
[1–6], most of them have good spectral and thermal properties.
Sr
3
Y(BO
3
)
3
crystal is one of them, it is isostructural with
Sr
3
Sc(BO
3
)
3
, which crystallizes in the R
3 (No. 148) structure [7].
The Yb-doped Sr
3
Y(BO
3
)
3
crystal has broad emission bandwidth,
in the actual state of the art, one of the broadest for an Yb-doped
crystal. A 69 femtosecond pulse laser with 80 mW average power
had been produced [2]. But a drawback with the Yb:Sr
3
Y(BO
3
)
3
crystal is its brittleness, which limited it’s application. The Stack
family with formula A
6
MM
0
(BO
3
)
6
, where A = Sr, Ba, Pb, or Ln
(lanthanide) and M, M
0
= +2, +3, or +4 metal cations belongs to
the trigonal system with space group R
3, is derived from the struc-
ture of the compound Sr
3
Sc(BO
3
)
3
. Its structure can be simply
described as: the metal-centered octahedra (MO
6
and M
0
O
6
) linked
by BO
3
groups to form chains, these chains are connected together
by the 9-coordinate Sr atoms to form a 3D framework. The MO
6
octahedron is larger and trigonally elongated and shares vertexes
with the 9-fold site, while the M
0
O
6
is trigonally compressed and
shares its triangular faces with the 9-fold site. When A = Sr atom,
M=M
0
= Sc atom, A
6
MM
0
(BO
3
)
6
corresponds to Sr
3
Sc(BO
3
)
3
com-
pound, on the other hand, when M = Y and M
0
= Sc, Sr
6
YSc(BO
3
)
6
compound is formed [8–10].InA
6
MM
0
(BO
3
)
6
compounds, the large
ion usually occupies the M site, whereas the small ion prefers to
occupy the M
0
position. However, in some cases, they can statisti-
cally occupy the same site, which leads to a partial disordered
structure. For example, in Sr
6
HoSc(BO
3
)
6
, the occupancy of M site
is 89% Ho and 11% Sc atoms, whereas the occupancy of M’ site is
93% Sc and 7% Ho atoms [8]. It is generally believed that the disor-
dered structure would result in the broad absorption and emission
bandwidth of laser crystals, which will beneficial to diode pumping
and production of ultrashort pulses. Moreover, as the ionic radius
of Sc
3+
is about 20% smaller that that of Y
3+
, which will make the
crystal structure of Sr
6
YSc(BO
3
)
6
more compact than that of
Sr
3
Y(BO
3
)
3
, this may improve the thermal and mechanical strength
of the material.
Nd
3+
doped Sr
6
YSc(BO
3
)
6
crystal had been grown by the
Czochralski method [11]. However, the thermal properties and
polarized spectroscopic characteristics of the crystal have not been
investigated, and they are very important for evaluating laser
performances and designing of laser device. Therefore, in this paper,
we report the growth, mechanical, thermal and polarized
spectroscopic characteristics of Nd
3+
:Sr
6
YSc(BO
3
)
6
crystal.
http://dx.doi.org/10.1016/j.optmat.2015.01.049
0925-3467/Ó 2015 Elsevier B.V. All rights reserved.
⇑
Corresponding author. Tel.: +86 591 83711451; fax: +86 591 83714636.
E-mail address: lzb@fjirsm.ac.cn (Z. Lin).
Optical Materials 43 (2015) 66–70
Contents lists available at ScienceDirect
Optical Materials
journal homepage: www.elsevier.com/locate/optmat