New data relating to flux growth, composition, homogeneity and physical characteristics of (R,Y)Al-3(BO3)(4) (R = Tm or Yb) crystals are discussed. Single crystals have been obtained using K2MO3O10-based fluxes by spontaneous nucleation as well as by the top-seeded solution growth at cooling rates of 4.8-12 degrees C/day and 0.2-5 degrees C/day, respectively, in the temperature range from 1120 to 900 degrees C. It is found that the average Tm and Yb segregation coefficients are close to unity, and vary from 0.80 to 1.02, as a consequence of minor difference in the sizes between Y3+ and R3+ cations. Two morphological types of (Tm,Y)Al-3(BO3)(4) crystals have been revealed. The average thermal expansion coefficients of Yb:YAB along a- and c-axis are measured as 2 x 10(-6)/K and 9.7 x 10(-6)/K, respectively., in the temperature range of 298-573 K. The specific heat of the Yb:YAB crystal at room temperature is found to be 0.76 J/g K, implying that this material can exhibit significant resistance to laser damage. Over 1.1 W of green emission has been obtained from a diode pumped 3 x 3 x 3 mm 3 Yb:YAB crystal. The conversion efficiency of diode to green is 10%. High beam quality of green and IR emission can be easily attained due to the good crystal quality and lack of thermal effects. (c) 2005 Elsevier B.V. All rights reserved.