Cr

3+

and Nd

3+

have been widely used as an optical activator in solid state luminescent and laser materials. A lot of works on Nd

3+

and Cr

3+

co-doped crystals and glasses have been made

in which the sensitive ion Cr

3+

can increase the absorption

pump efficiency and quantum efficiency to Nd

3+

due to the superimposition of emission of Cr

3+

and absorption of Nd

3+

. Crystals have high quantum efficiency

but cannot be synthesized into large size materials. Glasses can not meet the demands of applications because of low quantum efficiency. Glass-ceramics are glass-crystallite composites where the crystallites are developed by heat treatment of already formed glass. The activator doped glass-ceramics have the merits and characteristics of glass

crystals and ceramics

and are capable of cheap fabrication of large dimensions of devices. In this paper

the transparent glass-ceramics B

2

O

3

-Al

2

O

3

-SiO

3

codoped by Cr

3+

and Nd

3+

were prepared by heating in one step process according to the principle of phase segregation. The main crystalline phase checked by XRD is a mullite solid solution. Absorption

emission spectra and lifetime of samples were measured. The distribution of sites for Cr

3+

and Nd

3+

in samples and the spectroscopic characteristics were analyzed and discussed by contrasting co-doped samples with singly-doped ones. The absorption spectra of co-doped sample is approximately equal to the superimposition of absorption of singly-doped Cr

3+

on that of singly-doped Nd

3+

sample. The intensity of emission at 700nm for the co-doped sample by 647nm excitation is only 65% of that of singly-doped Cr

3+

and the intensity of emission at 700nm and 775nm by 568nm excitation are 87% and 70% respectively. The Nd

3+

lifetime observed at 1060nm increased by 45% due to radiation trapping in the co-doped sample compared to the sample containing Nd

3+

only. It is shown that there are radiative and nonradiative energy transfers from Cr

3+

to Nd

3+

. The Cr

3+

ions almost universally favor octahedral coordination in crystalline phase

and Nd

3+

would concentrate in the residual glass phase. The distribution of Cr

3+

ions will affect on the spectroscopic characteristics of Cr and Nd doped glass-ceramics. From our experiments and studies

the authors came to realize that a stronger process of radiative and nonradiative energy transfer from Cr

3+

to Nd

3+

was observed in the transparent B

2

O

3

Al

2

O

3

Si

2

glass-ceramics co-doped with Cr

3+

and Nd

3+

.The distribution of Cr

3+

sites characterized by crystal field parameter

Dq

affected on the energy transfer process

where low field Cr

3+

sites have a higher energy transfer efficiency than that under high field.