Table 1 Sintering process, mean grain size and dielectric properties of some LnCu₃Ti₄O₁₂ (Ln = Na_1/2Bi_1/2, Na_1/2Sm_1/2, Na_1/2Eu_1/2, Na_1/2La_1/2, Na_1/2Y_1/2, Na_1/3Ca_1/3Bi_1/3 and Na_1/3Ca_1/3Yb_1/3 etc.) ceramics.

Bi_1/2Na_1/2Cu₃Ti₄O₁₂

Pechini method

1000 °C for 10 h

3.2

2.77 × 10³

0.11

³⁰

Na_1/2Bi_1/2Cu₃Ti₄O₁₂

Sol–gel

1000 °C for 3 h

2.2

≈ 10⁴

–

⁹

Na_1/3Ca_1/3Bi_1/3Cu₃Ti₄O₁₂

Solid state method

1060 °C for 5 h

2–20

2.59 × 10⁴

0.038

²⁷

Na_1/2Sm_1/2Cu₃Ti₄O₁₂

Sol–gel

1050 °C for 18 h

3.67

8.04 × 10³

0.045

³¹

Na_1/2Sm_1/2Cu₃Ti₄O₁₂

Solid state method

1110 °C for 10 h

–

7.02 × 10³

0.041

³²

Na_1/2La_1/2Cu₃Ti₄O₁₂

Solid state method

1080 °C for 5 h

2–4

6.1 × 10³

0.037

³³

Na_1/2La_1/2Cu₃Ti₄O₁₂

Spark plasma sintering

925 °C for 10 min

0.3

 > 10³

–

¹⁴

Na_1/2Y_1/2Cu₃Ti₄O₁₂

Solid state method

1085 °C for 5 h

11

1.4 × 10⁴

0.04

¹⁸

Na_1/2Y_1/2Cu₃Ti₄O₁₂

Solid state method

1110 °C for 10 h

10.32

1.8 × 10⁴

0.03

²⁸

Na_1/2Y_1/2Cu₃Ti_4.1O₁₂

Solid state method

1090 °C for 5 h

4.06

2.56 × 10⁴

0.022

⁸

(Na_1/3Ca_1/3Yb_1/3)Cu₃Ti₄O₁₂

Sol–gel

1075 °C for 12 h

0.18–0.4

5488

0.075

²¹

Na_1/2Sm_1/2Cu₃Ti₄O₁₂

Solid state method

1000 °C for 10 h

19.73

5.5 × 10³

0.055

This work

Na_1/2Eu_1/2Cu₃Ti₄O₁₂

Solid state method

1000 °C for 10 h

16.9

4.7 × 10³

0.066

This work