Help needed with Repeated Measures ANOVA - how to correctly specify nested effect?

Hi everyone, I need some advice regarding nested effects.

My data set has the following variables:

HeatingRate = dependent variable
Individual (n = 4) = fixed
Temperature gradient (n = 3) = fixed
Trial (n = 3 per temperature gradient per individual) = random

I'm interested in knowing whether the heating rates differ between differ between temperature gradients and between individuals (not a random effect).

I'm, however, unsure how to correctly incorporate trial as a random effect (something I've been struggling with for a while...)

Can anyone tell me whether the nested effect is correctly specified?

lmer(HeatingRate ~ TemperatureGradient * Individual + (1|Individual|TemperatureGradient|Trial))