Yb3+ energy-transfer in the Nd3+ and Yb3+ co-doped Sr0.6Ba0.4(NbO3)2 (SBN) crystal is investigated by using pulsed and steady state laser spectroscopy. Spectroscopic data revealed that the energy transfer occurs via a non-radiative process. The efficiency of this energy transfer was estimated from spectral data in around 35%. Back energy transfer is not observed at the 295-415 K temperature range. A marked reduction in the luminescence intensity of Yb3+ ions directly excited into their ²F7/2 ²F5/2 transition, taking place at around 345 K, is due to the ferro to paraelectric phase transition in SBN. This thermal behavior, which is not clearly manifested when Yb3+ ions are excited via Nd3+ ions, has been explained in terms of structural changes taking place around the Yb3+ ions when the crystal becomes non-polar.]]>
Yb3+ en el cristal Sr0.6Ba0.4(NbO3)2 (SBN) codopado conYb3+ y Nd3+ es investigada mediante espectroscopia láser pulsado y estacionario. Datos espectroscópicos revelaron que la transferencia de energía ocurre vía un proceso no-radiativo. La eficiencia de esta transferencia de energía fue estimada de los datos espectrales en alrededor de 35%. La transferencia de energía a la inversa (Yb3+ Nd3+) no es observada en el rango de temperaturas 295-415 K. Una marcada reduccion en la intensidad de luminiscencia de los iones Yb3+ directamente excitados dentro de su transición ²F7/2 2F5/2, ocurriendo en alrededor de 345 K, es debida a la transicion de fase ferro a paraeléctrica de SBN. Esta conducta térmica, la cual no es claramente manifestada cuando los iones Yb3+ son excitados vía los iones Nd3+, ha sido explicada en terminos de cambios estructurales ocurriendo alrededor de los iones Yb3+ cuando el cristal se convierte en no-polar.]]>
Energy transfer in Sr0.6Ba0.4Nb2O6 through its ferroelectric phase transition
U. Caldiñoª, E. Martín–Rodríguezb, D. Jaqueb and J. Garcia Soléb and M. Bettinellic
ª Departamento de Física, Universidad Autónoma Metropolitana–Iztapalapa, PO Box 55–534, 09340 México, DF, México, e–mail: cald@xanum.uam.mx
c Dipartimento Scientifico e Tecnológico, Universita di Verona, and INSTM, UdR Verona, StradaLe Grazie 15,I–37314 Verona, Italy, e–mail: marco.bettinelli@univr.it
Recibido el 9 de noviembre de 2007 Aceptado el 9 de agosto de 2008
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Abstract
Resonant Nd3+ Yb3+ energy–transfer in the Nd3+ and Yb3+ co–doped Sr0.6Ba0.4(NbO3)2 (SBN) crystal is investigated by using pulsed and steady state laser spectroscopy. Spectroscopic data revealed that the energy transfer occurs via a non–radiative process. The efficiency of this energy transfer was estimated from spectral data in around 35%. Back energy transfer is not observed at the 295–415 K temperature range. A marked reduction in the luminescence intensity of Yb3+ ions directly excited into their 2F7/22F5/2 transition, taking place at around 345 K, is due to the ferro to paraelectric phase transition in SBN. This thermal behavior, which is not clearly manifested when Yb3+ ions are excited via Nd3+ ions, has been explained in terms of structural changes taking place around the Yb3+ ions when the crystal becomes non–polar.
Keywords: Energy transfer efficiency; luminescence; spectroscopy; SBN; Nd3+; Yb3+; phase transition.
Resumen
La transferencia de energía resonante Nd3+Yb3+ en el cristal Sr0.6Ba0.4(NbO3)2 (SBN) codopado conYb3+ y Nd3+ es investigada mediante espectroscopia láser pulsado y estacionario. Datos espectroscópicos revelaron que la transferencia de energía ocurre vía un proceso no–radiativo. La eficiencia de esta transferencia de energía fue estimada de los datos espectrales en alrededor de 35%. La transferencia de energía a la inversa (Yb3+ Nd3+) no es observada en el rango de temperaturas 295–415 K. Una marcada reduccion en la intensidad de luminiscencia de los iones Yb3+ directamente excitados dentro de su transición 2F7/2 2F5/2, ocurriendo en alrededor de 345 K, es debida a la transicion de fase ferro a paraeléctrica de SBN. Esta conducta térmica, la cual no es claramente manifestada cuando los iones Yb3+ son excitados vía los iones Nd3+, ha sido explicada en terminos de cambios estructurales ocurriendo alrededor de los iones Yb3+ cuando el cristal se convierte en no–polar.
Descriptores: Transferencia de energía; luminiscencia; transiciones de fase; espectroscopia; SBN; Nd3+; Yb3+.
This work has been supported by the Spanish Ministry of Science and Technology under project contract MAT2004–03347 and by the CONACyT (México) under project contract 43016–F.
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²F5/2 transition, taking place at around 345 K, is due to the ferro to paraelectric phase transition in SBN. This thermal behavior, which is not clearly manifested when Yb3+ ions are excited via Nd3+ ions, has been explained in terms of structural changes taking place around the Yb3+ ions when the crystal becomes non-polar.]]>
Yb3+ energy–transfer in the Nd3+ and Yb3+ co–doped Sr0.6Ba0.4(NbO3)2 (SBN) crystal is investigated by using pulsed and steady state laser spectroscopy. Spectroscopic data revealed that the energy transfer occurs via a non–radiative process. The efficiency of this energy transfer was estimated from spectral data in around 35%. Back energy transfer is not observed at the 295–415 K temperature range. A marked reduction in the luminescence intensity of Yb3+ ions directly excited into their 2F7/2